Neil1993

yeah. But the one in the video doesn't look like it would really get much thrust. I don't think the nozzle converges enough to make it much more than a showpiece.

So I saw this video a while back about a crazy Swedish guy who made an RC airplane with an afterburner. What I was curious about, is how much this could actually be used to increase thrust. I'm probably going to try simulating it in 2D on my own soon, but if anyone knows of a similar project, could you please point me in the right direction? I'll keep you all apprised of my progress. (here's the video)

If I might stick my nose into this discussion, I think that anyone doing research/design work relating to rockets or rocket propulsion might consider themselves a rocket scientist. I am working on a project involving rockets right now and I think it would be unfair to not include the software and electrical engineering students working with us, as well as those in physics and math. They are all contributing to the final product and they have at least a rudimentary understanding of the physics involved in rocket flight.

Tsiolkovsky's famous equation is only really meant for a rocket already in deep space. Where forces like drag and gravity are variable with velocity and altitude, there isn't really any one-step equation that can be used to solve for the altitude. You would have to do a numerical solution using time-steps. I guess you could try to do this with sufficiently steps and then try to curve fit the entire thing, but I don't think this is what you were going for, was it?

Chuck Yeager's bias may be from his association with Scott Crossfield, a pilot who beat him to mach 2. Scott became a civilian test pilot for the X-15 program but almost all the record breaking flights were reserved for the air force pilots. Apparently, this annoyed him greatly.

You must be psychic. It is indeed for IREC

Almost all correct! The nose is balsa which has been laminated with fiberglass and capped with a plastic tip. We're probably going to replace it with a hollow fiberglass nose.

I have built quite a few. In fact, I have 2 waiting in the wings right now (they both have yet to launch). this is one that's meant to carry a 10 lbs payload :

Unfortunately, it wasn't ready for the first launch time, so we're improving it for the next launch event which is a little less than a year away. In simulation, it has a maximum velocity of Mach 0.83 and it should travel to around 3160 m. It was built to carry a 10 lbs payload.

yeah, it isn't so good for that... We had to make sure that the aerodynamic heating and the pressure change wouldn't be serious enough to cause any damage. This was the first prototype:

manufacturing is actually extremely simple. The robot does it all. It's the material that ends up being so costly, as well as the tools (that machine is the only one of its kind in Canada ). It is always better than CF which is made by hand techniques. It is more uniform and has better dimensional accuracy, which results in it being stronger and easier to design for. As well, PEEK is stronger than most other epoxies that are used. Beyond that, the properties of the part produced depend on the fiber angles that you chose to work with. The material was actually made specifically for the rocket (the rocket came first). We found that the university had those facilities so we decided to go big on it. I got to learn a lot.

In terms of structure, the material we used managed to improve the rocket tremendously. We used a tube that was 2 mm thick, but we would still have been in the green had we halved that value. I'm not to sure about the high/low temperature properties of the material, but it didn't particularly matter in this project, as the fuselage wouldn't be encountering any serious temperature extremes. However, my colleagues working in propulsion have been looking into building composites nozzles, though I'm not really sure about what progress they've made.

While working on an undergraduate project at my university, I got the opportunity to make a rocket fuselage with an interesting carbon fiber composite. Unlike most carbon fiber composites which use thermosets like epoxy as matrix (the stuff that isn't the fibers) this one used PEEK thermoplastic. I very quickly fell in love with the stuff. It manages to be as light as most professional carbon fiber composites with a density of around 1.44 g/cc but it is also might be surprisingly strong. It was supposed to withstand 4000 N in compression but simulations indicated that it could go up to almost ten times that number. Overall, it manages to be superior to aluminum in most ways (again, this is according to simulation). To achieve this, we stacked sixteen layers of the material in four different directions. This can be seen below: Another great thing about it is that it rolls off the machine ready to go, only needing for the rough ends to be cut. The manufacturing process can sometimes take less than half a day. You can see the robot that is used to make it as well as a finished section below: It also has very good dimensional accuracy (mostly due to the fact that it was done by a robot). This means that couplers are a piece of cake. We made one for the rocket's payload bay and its fit was pretty much perfect: Are there any downsides to this material? Of course! The fact that it is made with a thermoplastic means that it is weaker than other composites at higher temperatures (it melts at around 343 C which is still higher than most thermoplastics). The biggest problem, however, was the cost. For us, it was about 950 CAD per meter, which puts it out of the range of most people. This is, of course, assuming that you can get access to one of the robots that does this. It is possible that the technology will become more accessible in the future, at which point I hope that its use will become more widespread in rocketry or space applications. Overall, working with this material was a worthwhile experience and I hope that I've imparted some of my love and interest for composite materials science to the reader.

The theory behind the workings of a warp drive is that you could start with an initial low velocity (let's say 3000 m/s). You would create a warp in space which would give you an apparent velocity of FTL (or 0.3 in your case) while still having an actual velocity of 3000 m/s. You could think of the warp like a bridge and the initial velocity of 3000 m/s as the velocity necessary to cross the bridge. You would then emerge from your warp with a velocity of 3000 m/s relative to your origin. All told, you would still need to perform various burns to reach orbit, but it would probably less than trying to decelerate 0.05c. At least, that's how I think it works

The cruising altitude of this missile while it was engaged in its supersonic bombing run was no more that 150 m from the terrain. Also, if shot down, the core would probably spread itself over a very large area. It's unlikely that the core inside such a vehicle would remain in one piece long enough to go into meltdown during a crash.

If you were absolutely certain that the debris would be landing on a large population center (the massive KSP super computer says so) then you could use lasers or some other tool to break up some of the floating pieces so they're small enough to burn up completely. Then you could try to attach a rocket to a docking port and deorbit the whole station manually so that it lands in the ocean. If you're still worried about the debris, you could use some kind of giant net-like device to scoop it up.

from the articles you provided, it appears that it can whistand stresses up to 400 MPa, depending on the sample being used. As well, its density appears to vary between 1.2 and 2.96 g/cc. It doesn't appear that it has been tested under irradiated conditions, but then again, I only skimmed the articles. If you were wondering about the effects of radiation because you wanted to know how it would fare in space, then check these guys out: http://spaceconcordia.ca/ They will be launching a satellite (in 2016, if it wins) which will investigate the effects of outer space on self-healing composites. Finally, your fourth question: if you were wondering if pre-fabricated sections could could be transported into space and then assembled without a bonding agent, then probably yes. However, if you were wondering if the material could be formed in space, I don't know. I'll try to read through the documents later. I just don't have much time right now.

could you maybe provide a link to where you saw this material? I have some friends who are working on something very similar. If it's anything like what they're using, I'll be able to get you some good info.

the point he (jwenting) was trying to make is that the shrapnel is considerably more deadly to a vehicle possessing a higher velocity. Say a piece of flak moving at 50 m/s and weighing 0.25 Kg impacts a plane moving in the opposite direction at 150 m/s. In this case, the flak's speed relative to the plane will be 200 m/s and its kinetic energy relative to the plane will be 5 KJ. However, if the same piece of flak hits a SLAM moving at 1020 m/s (~ mach 3), its relative kinetic energy will be more than 143 KJ. This would be able to cause instant and catastrophic damage to the vehicle. However, if it were shot down over your country, the fallout from the crash (or the plane being shredded into a million pieces in midair) would still cause significant damage.

The Russian's planned Hypersonic missile should be fast enough to fit the bill, that is, if it is ever finished.

I have been seeing this crop up in a few of the books that I have been reading. While Project Pluto was one of the more cruel and ruthless weapons designed by the United States during the cold war, it still remains an interesting technical concept. I have summarized the history of the project, while mainly focusing on the technical aspects, in the following paragraphs. Conception and Requirements It was the mid '50s when the need for a weapons project such as Project Pluto was first rationalized. The United States wanted something that would be invisible to enemy radar and unattainable by conventional anti-aircraft weapons. The proposed solution was a supersonic, low-altitude missile (SLAM). The idea is that the missile would fly so close to the ground that radar couldn't detect it, and it would go so fast that it could not be shot down. However, sustaining speeds that great (approximately mach 3) at such a low altitude required ridiculous amounts of power. The answer? A nuclear ramjet, of course! Design: The Vehicle The vehicle itself had obviously been designed with supersonic speeds in mind. It had a pointed nose and very swept wings. The vehicle, in fact, was practically a rocket, as the three control surfaces that it had were small compared to the rest of the vehicle and evenly spaced at 120 degrees. Underneath it was the large ramjet intake which earned it the nickname "The flying crowbar." Since the vehicle was to be very large and complicated, the designers figured that it would be a waste of resources to use it to deliver a single warhead. So, it was designed to carry more than a dozen thermonuclear warheads which could be used on multiple targets. The challenges of such a craft were, understandably, enormous. For instance, the body had to endure a dynamic pressure greater than that felt by the X-15. As well, the ramjet had to handle heat loads in excess of 800 degrees Celsius and most of the components within the rocket had to be able to operate in an irradiated environment. The vehicle was supposed to be launched with three strap-on boosters. Once reaching sufficient speed, the reactor was engaged and the nuclear ramjet kicked in. Design: The Powerplant By far the most difficult part of the vehicle to design was the nuclear motor. This was something that had never been previously attempted. It had to produce more than 500 megawatts of power while still being small enough to fit in a plane. Obviously, it had to be unshielded. However, this meant that the conditions within the reactor were more extreme than anything had ever been designed for. the temperatures in the center of the reactor exceeded 1370 degrees Celsius, which is well above the operating temperatures of most alloys. In the end, the core was made of ceramics, molybdenum, advanced steel and Hastelloy R-235. Even then, it was designed at a low factor of safety, as the materials were operating very close to their thermal maximum while still resisting the incoming air, which created up to 2400 Kilo-Pascals of pressure on the core. Testing the Nuclear Ramjet Despite the almost impossible technical requirements of the motor, two powerplants were actually built and tested. The first one tested was the Tory II-A. It was a scaled down version which only generated 155 megawatts of power, processed 320 Kilograms of air every second and burned at 1230 degrees Celsius. A large facility had to be built to compress and preheat the air required the run the engine. The first test lasted only a few seconds before all the pre-heated and compressed air ran out, but it was a complete success. Next, a full scale test engine, called the Tory II-C, was built. As well, the facilities required the store the compressed air were upgraded so that they could fuel the bigger engine for a longer period of time. After a "small" test with reduced thrust, the scientists put the pedal to the metal and tested the engine at it's maximum operational limits. It produced 156,000 newtons of thrust and 513 megawatts of power during its five minute burn and consumed almost a ton of air every second. The End of the Program Thankfully, this missile was never deployed as an actual weapon. In fact, a full prototype was never even built and tested. There are a myriad of reasons proposed as to why it was shut down. It could have been that this weapon was just too deadly and provocative. Another plausible reason is that the hundreds of ICBMs and submarine based missiles rendered it redundant. Finally, it could be that it was almost impossible to test the missile without irradiating its test range and rendering the area uninhabitable. (Edit: Read rdfox's reply for a more in depth explanation of the program's cancellation) Despite the project's sinister purpose, many of the technologies developed went on to be used in commercial and civilian applications, meaning that the money dished out by the government did not, in fact, go to waste. Sources Spaceship Handbook, by Jack Hagerty and Jon C. Rogers http://en.wikipedia.org/wiki/Project_Pluto Note: This post tries to focus on, and create discussion over, the technical challenges of such a device.

The best use for interstellar travel is for ensuring the survival of the human race by spreading ourselves across the galaxy. Since our current ability to do this is, shall we say, limited, we'll have to take small steps first. Kryten is quite right when he says that life can be discovered using spectroscopy. A good course of action would be to scout for interstellar targets using more and more advanced telescopes while we do as NASAFanboy suggested: "focus on our own solar system, and slowly build infrastructure to expand to Mars and the Moon." This is probably the way we're going right now, anyways.

One case where it could matter, is with neutral stabiliy. In this case, the CoP and CG have the same location. This means that the rocket will shift between positive and negative stability depending on the flight conditions leading a very erratic and unpredictable flight path. Note: As a general rule, a rocket of this kind will tend to fly towards the nearest crowd of bystanders. Should a crowd of bystanders be unavailable, it will fly towards the nearest easily damaged property.

I was addressing Wheffle's comment regarding launching rockets and I admit that I know little about reentry aerodynamics. Most of what I have studied are the dynamics of ascending rockets, specifically rockets using passive stabilization. As well, while I imply the general assumption that the CoP remains stationary, this is never the case. An ascending rocket's CoP will change for different angles of attack and airspeeds. However, assuming that a rocket has a stationary center of pressure is probably good enough for KSP. I will definitely look into reentry aerodynamics some more. It is not something I know enough about.

I don't know too much about re-entery, but I might be able to help with rocket ascent. A flying body has two centers that you need to consider; the cente of mass and the center of pressure. You already know what the center of mass is. The center pf pressure can be considered as the point where the total sum of a pressure field acts on a body. In a rocket exhibiting positive stability (this is what you want) the center of gravity will be closer to the nose than the center of pressure. Why is this so? when a rocket is perturbed and at a non-zero angle of attack (the airstream isn't parallel to the longitudinal axis of the body) the body generates lift, as anything at a non-zero angle of attack would. This lift, which acts at the center of pressure, restores the rocket to a zero angle of attack. Here's a picture to make this more clear: Side note: you can have unstable rockets that still fly. They just require a ridiculous amount of computer control to keep going straight.